Polymers with covalently cross-linked networks are commonly referred to as thermosets. Thermosets get this name from the fact that they cannot flow upon heating and thus cannot be reshaped and recycled. Conventional network polymers, such as thermosets, obtain their shape as they are synthesized. After taking shape, they cannot be reprocessed and recycled, see Aklonis & MacKnight, Introduction to Polymer Viscoelasticity, 2nd ed., New York: Wiley, 1983.
In contrast to thermosets, network polymers with dynamic covalent bonds (DCB) allow for bond exchange reactions (BER) that can alter network topology. In DCB polymers, the covalently connected backbone of the macromolecular chain can cleave then reconnect through bond exchange reactions (BER). Such dynamic covalent bond reformation activities do not change the network topology and properties, but enable macroscopic stress relaxation and material welding.
DCB polymers that have been synthesized either require the inclusion of expensive catalysts (see, for example, WO2014086974A1 to Leibler et al.) and/or have BER that are highly active under ambient conditions, and thus cannot replace most thermoset materials.